1. Field of Invention
The present invention relates to a fan and a motor thereof and, in particular, to a fan and a three-phase coreless motor thereof.
2. Related Art
Motors are devices to transform electrical energy into mechanical energy, and have been applied to many products such as fans, optical disc drives, hard disk drives, optical devices or vehicle devices in daily lives. Though the motors can be classified into various types, the fundamental operation principle of the motors is electromagnetic effect.
As shown in FIG. 1A, a conventional three-phase coreless motor 1 includes a bearing structure 11 and a rotor structure 12. The rotor structure 12 includes a shaft 121, a magnetic housing 122 and a magnetic ring 123. The shaft 121 is disposed in the bearing structure 11. The magnetic housing 122 is connected to the shaft 121. The magnetic ring 123 is disposed around and connected to the inner surface of the magnetic housing 122. In addition, the motor 1 further includes a stator structure 13, which includes a three-phase coreless coil assembly 131 disposed around the shaft 121 corresponding to the magnetic ring 123 perpendicularly. When applying current to the three-phase coreless coil assembly 131, it generates electromagnetic effect with the magnetic ring 123 to drive the shaft 121, the magnetic housing 122 and the magnetic ring 123 to rotate.
FIG. 1B is a three-dimensional figure of the three-phase coreless coil assembly 131. As shown in FIG. 1B, the three-phase coreless coil assembly 131 includes, for example, 6 groups of coils, and the coils with same phase such as the coils 131a-1 and 131a-2, the coils 131b-1 and 131b-2, and the coils 131c-1 and 131c-2 are disposed corresponding to each other, respectively. To promote the operation efficiency of the motor 1, the ratio of the coils generating effective electromagnetic effect with the magnetic ring 123 of the rotor structure 12 in the three-phase coreless coil assembly 131 has to be increased. It means that the slot-fill factor in the same space shown in FIG. 1B has to be increased. In other words, the ratio of the effective coils of the three-phase coreless coil assembly 131 must be increased.
However, the ratio of the effective coils of the three-phase coreless coil assembly 131 is frequently restricted due to the limited space of the stator structure 13 of the motor 1. Thus, without expanding the space of the stator structure 13, it is impossible to highly increase the ratio of the effective coils of the three-phase coreless coil assembly 131. Consequentially, the operation efficiency of the motor 1 cannot be further enhanced.
Therefore, it is an important subject of the invention to provide a three-phase motor with the high ratio of the effective coils of the stator structure for promoting the operation efficiency.